lib::dualpopen

lib.cpp

@@ -5,9 +5,35 @@
 #include <cassert>
 #include <cstring>
 #include <fcntl.h>
+#include <unistd.h>
 
 namespace lib
 {
+	std::pair<FILE *, FILE*> dualpopen(const char * cmd)
+	{
+		int fd_stdin[2];
+		int fd_stdout[2];
+		assert(pipe(fd_stdin) == 0);
+		assert(pipe(fd_stdout) == 0);
+		int r = fork();
+		assert(r>=0);
+		if(r>0)
+		{
+			close(fd_stdin[0]);
+			close(fd_stdout[1]);
+			return {fdopen(fd_stdin[1], "w"), fdopen(fd_stdout[0], "r")};
+		}
+		else
+		{
+			close(fd_stdin[1]);
+			close(fd_stdout[0]);
+			assert(dup2(fd_stdin[0], 0) == 0);
+			assert(dup2(fd_stdout[1], 1) == 1);
+			execl("/bin/sh", "sh", "-c", cmd, (char *) NULL);
+		}
+		exit(1);
+	}
+
 	vector<int> gen_arr_other_car_of_type(int n,vector <int> input)
 	{
 		assert(input.size() == 2*n);

lib.h

@@ -26,6 +26,8 @@ namespace lib
 	int calc_score(int n, vector<bool> out);
 	int calc_mistakes(int n, vector<int> input, vector<bool> out);
 	
+	std::pair<FILE *, FILE*> dualpopen(const char * cmd);
+
 	namespace internal
 	{
 		void format_args(char * verdict, int & verdict_len, int argc, char const* const* argv);